The invention relates to a video extractor for use in a pulse radar apparatus.
For the automatic processing of radar information in digital computers it is necessary to convert the analog radar signal into a digital form. Since the received analog signal contains a substantial amount of irrelevant data, such as noise, clutter, etc., video extractors are employed in pulse radars to reduce the computer load. The function of a video extractor is to extract usable information from the signal and to apply this information in a suitable form to the computer for further processing. Differences between radar systems and different applications demand different embodiments of such video extractors. It is therefore a primary object of the invention to provide a video extractor which, through numerous adjustable parameters, is adaptable to different types of radars and is suitable for many applications.
A fully universal extractor however cannot be realized. Adaptation to a specific radar system must done. The commonly known and simplest "moving window" extractor is dependent upon radar parameters, such that each type of radar requires its own design. Moving-window extractors are impracticable for short ranges, such as in harbors, in view of the dimensions and the small distance between the targets. The "detector accumulator", also of prior art, is considerably more flexible in this respect and gives a greater positional accuracy. Disadvantages of the latter type of extractor are a confined memory capacity and relatively complex logic circuitry. Another object of the invention is therefore to provide a video extractor in which the advantages of the two above-mentioned types are retained, whereas their disadvantages are obviated and a more flexible setting of the parameters can be achieved.